Internet DRAFT - draft-friel-pki-for-devices

draft-friel-pki-for-devices







Network Working Group                                           O. Friel
Internet-Draft                                                 R. Barnes
Intended status: Standards Track                                   Cisco
Expires: May 3, 2018                                    October 30, 2017


             PKI Certificate Identifier Format for Devices
                     draft-friel-pki-for-devices-00

Abstract

   This document defines a standard Subject field identifier format for
   certificates issued to Internet of Things (IoT) devices.  This will
   allow applications to easily and uniquely identify certificates
   issued to devices as opposed to certificates issue to services or
   users.  The certificates will adhere to standard Web PKI
   specifications thus ensuring interoperability with existing
   Certificate Authorities processes and workflows, and standard client
   and service libraries and applications.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on May 3, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Manufacturing vs. Deploy Time Certificates  . . . . . . . . .   3
   3.  Device Information Domain Name  . . . . . . . . . . . . . . .   3
     3.1.  IDevID Certificates . . . . . . . . . . . . . . . . . . .   3
     3.2.  LDevID Certificates . . . . . . . . . . . . . . . . . . .   4
   4.  Certificate Fields  . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Subject . . . . . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Subject Alternate Name  . . . . . . . . . . . . . . . . .   5
     4.3.  Extended Key Usage  . . . . . . . . . . . . . . . . . . .   5
     4.4.  Certificate Lifetime  . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   There is an increasing need for devices to be able to uniquely
   identify themselves and assert their identity, and associated
   identity attributes, using standard Web PKI techniques.  In order to
   faclitate issuing certificates to devices, this document defines a
   mechanism for uniquely identifying devices using a structured Subject
   field identifier that should be supported by all major Certificate
   Authorities (CAs), including those CAs that support
   [I-D.ietf-acme-acme].

   The use of Web PKI for the purpose of issuing device certificates has
   multiple benefits including:

   o  Existing code, processes, and policies for managing Web PKI
      certificates can be re-used

   o  Device certificates can be trusted by web browsers

   o  For small-scale device manufacturers, it is possible to use
      existing CAs to issue device certificates of this kind

   o  For more mature manufacturers, the use of structured DNS names to
      encode device information means that name-constrained intermediate
      CAs can be used to allow the manufacturer to issue device
      certificates independently of the root CA.




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   Previous attempts to uniquely identify device certificates have not
   proven to be broadly supported by common certificate management
   software libraries.  These include:

   o  [IEEE802.1AR] which defines a serialNumber field

   o  [RFC4108] which defines a hardwareModuleName field

2.  Manufacturing vs. Deploy Time Certificates

   Devices will typically have a unique certificate that is baked into
   the device at manufacturing time i.e. the device will leave the
   factory with a unique manufacturer installed certificate already
   baked in.  This certificate will typically be signed by a CA that the
   manufacturer controls, or a CA that the manufacturer explicitly
   authorizes.  This CA does not necessarily have be a public root CA
   that is trusted by web browsers.  This certificate is referred to as
   the Initial Device Identifier (IDevID).

   A common deployment requirement is that the end customer that
   purchases and deploys the device in their local domain will need to
   install a certificate on the device that is signed by a CA under
   their control, or signed by a CA of their choosing.  This certificate
   is referred to as the Locally Significant Device Identifier (LDevID).

3.  Device Information Domain Name

   A unique device identifier is encoded in a structured Device
   Information Domain Name Identifier (DIDN-ID) of the following form:

     <serial>.<model>.keyword.<domain>

   where "keyword" MUST be one of:

   _mDevice
   _device

   The fields "serial", "model" and "domain" are described in the
   following sections.

3.1.  IDevID Certificates

   IDevID certificates have the following form:

     <serial>.<model>._mDevice.<manufacturer>

   Where:




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   o  "manufacturer" is a fully-qualified domain name identifying the
      manufacturer of the device

   o  "_mDevice" is a mandatory keyword that indicates this is an IDevID
      installed at manufacturing time

   o  "model" is a manufacturer-chosen string that MUST identify the
      model or type of the device

   o  "serial" is a manufacturer-chosen string that MUST identify the
      specific serial number of this model

   The combination of "manufacturer", "model", and "serial" MUST
   uniquely identify the device.

3.2.  LDevID Certificates

   If the LDevID is issued by a public trusted CA, then the LDevID
   idenfitier format MUST follow the identifier format specified in this
   section.

   Where the LDevIDs are issued by private domain CAs that do not
   necessarily need to adhere to CA/Browser forum guidelines, it is
   strongly recommended that the private CA follows this identifier
   format specification.

   LDevID certificates have the following form:

     <serial>.<type>._device.<deployment-domain>

   Where:

   o  "deployment-domain" is a fully-qualified domain name identifying
      the local domain where the device is installed.  This will
      typically be a domain that the purchaser or owner of the device
      can assert ownership of

   o  "_device" is a mandatory keyword that indicates this is an LDevID
      installed during live deployment

   o  "model" this SHOULD be copied from the IDevID of the device

   o  "serial" this SHOULD be copied from the IDevID of the device

   The combination of "manufacturer", "model", and "serial" SHOULD
   uniquely identify the device.





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   If the customer who owns the device uses a public CA to issue the
   LDevID, and if the device "serial" number and/or "model" is
   considered sensitive or Personally Identifiable Information (PII),
   then the "serial" and "model" fields MAY be replaced with suitable
   alternate identifiers.  However, the public CA MUST ensure that the
   format and structure of the DIDN-ID adheres to this specification.

4.  Certificate Fields

4.1.  Subject

   Following the recommendations set out in [RFC6125], the Subject field
   of the certificate MAY contain the "commonName" field, set to the
   DIDN-ID for the device.

   The Subject field MAY also contain a "serialNumber" or
   "hardwareModuleName" field.

4.2.  Subject Alternate Name

   The certificate MUST contain a "subjectAltName" extension
   contataining a single "dnsName" entry with the DIDN-ID for the
   device.

4.3.  Extended Key Usage

   The certificate MUST contain an "extKeyUsage" extension with the
   values "id-kp-serverAuth" and "id-kp-clientAuth", and no other
   values.

4.4.  Certificate Lifetime

   IDevID certificates with "_mDevice" identifiers in their DIDN-ID MUST
   have a "notAfter" value of 99991231235959Z (i.e.  Y10K).

   It should be noted that at the time of writing, web browsers do not
   check for Y10K and will happily establish connections with endpoints
   whose identity certificate has a "notAfter" value of Y10K.

   LDevID certificates are issued during live deployment and MUST follow
   the standard lifetime and expiration requirements of the issuing CA.

5.  IANA Considerations

   [[ TODO: Register the "_device" and "_mDevice" labels ]]






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6.  Security Considerations

   [[ TODO ]]

7.  Informative References

   [I-D.ietf-acme-acme]
              Barnes, R., Hoffman-Andrews, J., and J. Kasten, "Automatic
              Certificate Management Environment (ACME)", draft-ietf-
              acme-acme-07 (work in progress), June 2017.

   [IEEE802.1AR]
              IEEE, ., "Secure Device Identity", 2017.

   [RFC4108]  Housley, R., "Using Cryptographic Message Syntax (CMS) to
              Protect Firmware Packages", RFC 4108,
              DOI 10.17487/RFC4108, August 2005,
              <https://www.rfc-editor.org/info/rfc4108>.

   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
              2011, <https://www.rfc-editor.org/info/rfc6125>.

Authors' Addresses

   Owen Friel
   Cisco

   Email: ofriel@cisco.com


   Richard Barnes
   Cisco

   Email: rlb@ipv.sx













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